1. Field of the Invention
The present invention relates to improvement of a nitride semiconductor laser device chip and of a nitride semiconductor laser apparatus including the same.
The nitride semiconductor described herein includes AlxGayInzN (0≦x≦1, 0≦y≦1, 0≦z≦1, x+y+z=1). In the nitride semiconductor, less than about 10% of the nitrogen element may be substituted with at least one element of As, P and Sb (provided that the hexagonal crystal system is maintained). Further, the nitride semiconductor may be doped with at least one of Si, O, Cl, S, C, Ge, Zn, Cd, Mg and Be.
2. Description of the Background Art
FIG. 6 is a schematic cross sectional view of a nitride semiconductor laser device chip disclosed in Japanese Patent Laying-Open No. 11-340571. In this laser device chip, an n-side clad layer 801, an n-side light guide layer 802, an active layer 803, a p-side light guide layer 804, a p-side clad layer 805, a p-side contact layer 806, an insulating film 807, and a p-electrode 808 are successively formed on one main surface of a nitride semiconductor substrate 800 comprised of a plurality of layers. An n-side contact layer 809 and an n-electrode 810 comprised of a plurality of layers are formed on the other main surface of substrate 800.
The laser device chip of FIG. 6 is 400 μm long in the longitudinal direction of its resonator, and 400 μm long in the width direction of the resonator.
The n-electrode side of the laser device chip of FIG. 6 is attached by thermocompression to a heat sink metallized with Au, and an Au wire is used to provide the chip with an electrical connection, to produce a nitride semiconductor laser apparatus.
As described above, in a conventional nitride semiconductor laser device chip, special attention has not been paid to its shape and dimensions, and the laser device chip normally has four sides of approximately the same lengths.
The inventors, however, have found through a variety of studies about the shape and dimensions of the nitride semiconductor laser device chip that the laser operating lifetime of the laser device is affected by the shape and dimensions of the chip.